Massively parallel high speed optoelectronic systems can have tens or even hundreds of channels, each working at up to 10 Gigabits per second. A typical system comprises either a receiver module or a transmitter module. FIG. 1 shows a top view of an exemplary prior art optoelectronic module 100 fabricated within an integrated circuit (IC) 110. The module 100 has an array of vertical cavity surface emitting lasers (VCSELs) 120 and a large number of high speed pads 130 disposed around the periphery of the IC 110. For clarity, not all of the high speed pads 130 are shown. Other pads such as supply pads and ground pads (not shown) are also typically disposed around the periphery of the IC 110. Typically, there are a total of 5 pads per channel, two pads are high speed pads 130 for electrical signal transmission, two pads are for power supply, and one pad is for ground. When optoelectronic module 110 is used as a receiver, VCSELs are replaced by photodetectors. For both receiver and transmitter, an additional optical subassembly that includes coupling and focusing optics and optical mulitplexers or demultiplexers reside on top of the VCSELs or photodetectors.
FIG. 2 illustrates an exemplary prior art evaluation board 200 used to test massively parallel optoelectronic modules. In FIG. 2, module 100 is placed on the evaluation board 200 and the individual high speed pads (e.g., high speed pads 130 of FIG. 1) are coupled via data lines 210 to a plurality of connectors 220. The connectors 220 are coupled via data cables 230 to either an evaluation tool such as a signal tester) or to a termination impedance 250.
Evaluating high speed optoelectronic systems present significant problems. For a massively parallel system, a manual evaluation system employing discrete connectors, cables and terminations requires a lengthy measurement session. Such systems are typically evaluated one or a few channels at a time in a process that involves tediously disconnecting and connecting the data cables 230. Because commercially available evaluation tools (e.g., evaluation tool 240) typically only allow a few inputs at a time, only a few channels of the device under test are connected at any given time to the evaluation tool. The rest of the channels are terminated by manually connecting each and every one of the rest of the connectors 220 to a suitable termination impedance 250. This results in a very tedious and time-consuming evaluation process involving repeatedly connecting and disconnecting cables manually. Additionally, accommodating all of these discrete components on an evaluation board results in a very large test platform that occupies an excessive amount of table-top space. Another disadvantage is that it is very expensive to purchase all of the high speed components necessary to build a conventional test platform.
Not only is the evaluation process tedious, but it is error prone. Since the connecting/disconnecting is all done manually, it is quite possible that one or more channels could be improperly terminated, resulting in an error in measurement. Furthermore, the constant connecting and disconnecting of leads causes wear of the connectors 220. Such connector wear can cause the connectors 220 to eventually fail to properly transmit the signal to module 100 and hence be an additional source of errors.